Alkylbenzenesulfonates are currently widespread as surface active agent, but their solubility in concentrated aqueous electrolytic solution is limited. For example, in cleaning of a metallic surface with a combination of an aqueous alkali solution and a surface active agent to remove animal or vegetable oils, nonionic surface active agents have generally been employed.
Nonionic surface active agents, however, show weaker dispersing ability as compared with anionic surface active agents. Further, since they exhibit no surface activity at temperatures above their cloud point, the temperature range of application to made of them is so limited.
On the other hand, anionic surface active agents, e.g., alkylsulfates, and nonionic emulsifying agents, e.g., polyvinyl alcohol, have been used for radical emulsion polymerization of vinyl monomers, e.g., vinyl acetate. The emulsion polymerization product obtained according to these systems have relatively large particle sizes of from one to several microns so that it is insufficient in chemical stability and mechanical stability.
There is hence a tendency to use anionic surface active agents which exhibit satisfactory solubility in highly concentrated aqueous electrolytic solutions and improve emulsion stability, such as alkyldiphenyl ether disulfonates as disclosed in U.S. Pat. No. 3,127,441 and alkenylsuccinates. Although the alkyldiphenyl ether disulfonates are effective to produce an emulsion polymerization product having a fine particle size and excellent emulsion stability, they are still unsatisfactory in performance, relatively expensive, and considerably limited in application.